Containers for storing small quantities of food and the like are well known and are widely used in households and elsewhere. These containers may be made of deformable plastic material such as polyethylene or the like, and typically come with an easily-detachable lid or closure to provide a seal with the container. Such foodstuff containers are available in a variety of shapes and sizes, and frequently are stored on refrigerator shelves or the like by stacking the containers one atop the other.
Food storage containers of the prior art generally have bottom surfaces and closures which are flat, or which at least have substantial flat portions. Although these flat tops and bottoms permit the containers to be stacked, a stack of two or more such prior art containers as a practical matter may be awkward or difficult to unstack. Containers of the same general size and configuration frequently have a surface-contacting base which can fit on top of the lid or closure for the container, due to the overall shape of the container. The closure typically has a raised peripheral rim surrounding the surface on which the base of a superadjacent container rests, and this rim can interfere with attempts to remove a selected container from a stack of such containers. This limitation on sideways displacement easily leads to tipping or knocking over a stack of containers, especially where several containers are stacked in an array from which one attempts to withdraw an intermediate container.
Attempting to improve unstackability of stacked containers simply by doing away with the rim surrounding the closure of the same size would be less than satisfactory. The close bottom-to-top conforming fit of such stacked containers provides a desired stability of stached containers. Moreover, the peripheral rim of the conventional closure provides the sealing engagement with the container, and thus is considered an important feature of the closure.